Apparatus for manufacturing discharge tubes

ABSTRACT

In a method and apparatus for manufacturing a discharge tube wherein an envelope of the discharge tube is connected to an evacuating pipe system to be evacuated and charged with an inert gas and operating substances required through the evacuating pipe system, said system is provided with a closable opening and while the inert gas is being discharged through the opening a capsule carrying the operating substance is inserted into the pipe system through said opening to charge the operating substance into the envelope.

United States Patent inventors Kazuyuki Ogawa Yokohama-shi; SatoshiNagano, Kawasaki-shi, Japan App]. No. 805,412 Filed Mar. 10, 1969Patented Mar. 30, 1971 Assignee Tokyo Shibura Electric Co., Ltd.Kawasaki-shi, Japan Priority Mar. 12, 1968, Aug. 23, 1968 Japan 43/15580 and 43/59833 APPARATUS FOR MANUFACTURING DISCHARGE TUBES 7 Claims,7 Drawing Figs.

U.S. Cl 316/30, 316/24 Int. Cl H01j 7/20 Field of Search 316/30 [56]References Cited UNITED STATES PATENTS 1,623,323 4/1927 Voorhis 3 l 6/30X 2,013,415 9/1935 Marden et a]... 3l6/3OX 2,171,705 9/1939 Leonard etal 3 l6/3OX Primary Examiner-H. A. Killy, Jr. Attorney-Irving M. WeinerABSTRACT: in a method and apparatus for manufacturing a discharge tubewherein an envelope of the discharge tube is connected to an evacuatingpipe system to be evacuated and charged with an inert gas and operatingsubstances required through the evacuating pipe system, said system isprovided with a closable opening and while the inert gas is beingdischarged through the opening a capsule carrying the operatingsubstance is inserted into the pipe system through said opening tocharge the operating substance into the envelope.

GAS 3 2? PATENTED MAR30 197i SHEET 1 OF 3 FIG.

VACUUM PUMP GAS IVACUUM PUMP FIGB IN VENTOR.

PATENTEH man IBTI SHEET 2 [IF 3 FIG? TIME

PATENTEflnARso 19?:

SHEET 3 BF 3 FIGS AFPARATUS FOR MANUFACTURING DISCHARGE TUBES Thisinvention relates to a method and apparatus formanufacturing dischargelamps or tubes containing an inert gas and one or more operatingsubstances sealed therein.

in the manufacture of discharge tubes, for example, discharge lampscontaining a mixed vapor of metals, in addition to an inert gas, a smallquantity of operating substances such as mercury and metal halides aresealed in the tubes. These metal halides have a property to absorbmoisture when exposed to the atmosphere, so that when moisture isinadvertently admitted into discharge lamps of this type during theirmanufacturing steps the characteristics of the lamps will be greatlyimpaired. Thus, it is necessary to prevent these metal halides fromabsorbing moisture or to keep them without exposing to the atmosphereduring the manufacturing steps of the lamps.

FIG. 1 shows a typical prior apparatus for manufacturing discharge lampswith due regard to this point. Thus, a glass envelope 3 mounted withelectrodes 2 and adapted to form a discharge lamp is connected to oneend of an evacuating pipe system 1 made of glass through a chipoffportion 4. Spaced apart branch pipes and 6 are connected to theevacuating pipe system. The other end of evacuating pipe system isconnected to a vacuum pump (not shown) and to a source of inert gas tobe filled in, for example, a source of argon gas, not shown, through asecond chipoff portion 8. Branch pipe 6 contains one of the operatingsubstances to be closed in, for example, a metal iodide 7 while branchpipe 5 contains mercury 9.

In the arrangement shown in FIG. 1 the entire system is evacuated to ahigh vacuum by the vacuum pump. After admitting argon gas under adesired pressure into the envelope the chipoff portion d is sealed offand then the envelope 3 and branch pipes 5 and 6 are separated from theremainder of the system. The separated portions are then suitablyslanted to transfer operating substances contained in branch pipes 5 and6 into the envelope. Thereafter chipoff portion 4 is sealed off and theenvelope is separated from the evacuating system, thus completing adischarge lamp.

However, the above described method has following defects. Moreparticularly, (I) As operating substances such as mercury 9 and metaldiode 7 are contained in the same vacuum system as the envelope 3 it isimpossible to create a high degree of vacuum. Further, as the degree ofvacuum that can be attained shoes the state of driving off impuritiesoccluded in the inner wall of the envelope and electrodes where it isnot possible to attain the desired high vacuum with the presence of theoperating substances in the branch pipes there is no way to confirm thatthe envelope 3 has been evacuated to the desired extent. (ll) Saidoperating substances tend to cause a loss in quantity due to spatteringor decomposition during the baking process, whereby the quality ofproduce will not be uniform. Further, decomposed products tend toaccumulate on cold portions of the evacuating system to rapidlydeteriorate the evacuating ability thereof. (III) The moisture that hasbeen contained in the decomposed products or substance 7 tends todeposit on the mercury 9 contained in branch pipe 5, and the depositedmositure is difficult to be completely removed from the system. (IV)Provision of branch pipes for exhaustion of each discharge lampcomplicates the process steps as well as the construction of theevacuation system.

it is therefore an object of tins invention to provide a new andimproved method and apparatus for fabricating high quality dischargetubes by a simple process without accompanying difficulties describedhereinabove.

Eriefly stated, in accordance with this invention, there is provided amethod of manufacturing a discharge tube having envelope in which aninert gas and a predetermined amount of operating substances are sealed,said method comprising the steps for evacuation of an evacuating pipesystem and the envelope connected thereto through a chipoff portion,supplying said inert gas to said envelope and said evacuating pipesystem, discharging said inert gas through an opening of said evacuatingpipe system, inserting said operating substance into said evacuatingpipe system through said opening so as to supply said substance intosaid envelope while said inert gas is being discharged through saidopening, said substance being hermetically sealed against theatmosphere, adjusting the pressure of said gas in said envelope to apredetermined value, and sealing off said chipoff portion to separatesaid envelope from said evacuating system.

The apparatus for carrying out the method outlined hereinabove comprisesan evacuating pipe system in the form of a manifold including a closableopening, a first and a second flow circuits respectively connected to avacuum pump and to a source of inert gas and a third circuit, one end ofsaid third circuit opening between said second circuit and said closableopening, the other end of said third circuit being connected to anenvelope of a discharge tube through a chipoff portion; and means whichis inserted into said evacuating pipe system through said closableopening to supply a selected operating substance into the envelopewithout exposing said substance to the atmosphere.

The invention is now described in conjunction with a preferredembodiment with reference to the accompanying drawings, in which:

FIG. I is a schematic representation of a prior apparatus for explainingthe prior method of manufacturing discharge tubes;

FIG. 2 is a diagram, partly in section, of the apparatus for carryingout this invention;

FIG. 3 is an enlarged sectional view of a portion of the apparatus shownin FIG. 2;

FIG. 4 is a diagram to show a modified apparatus for carrying out thisinvention;

FIG. 5 shows an enlarged sectional view of a portion of the apparatusshown in FIG. 4 to show the communication between a first evacuatingsystem and an envelope;

FIG. 6 is a view similar to FIG. 5 but wherein the communication betweenfirst and second evacuating systems and the envelope is interrupted; and

FIG. 7 is a diagram to show the effect resulting from discharging aninert gas from the opening of a system according to the invention.

One embodiment of this invention will now be described by referring toFIGS. 2 and 3 of the accompanying drawings. On one end of a manifold i0is provided a closable opening ll which may comprise a flange 12, anO-ring l3 fitted in a groove in the flange and a cover plate 114 clampedagainst the O-ring by means of bolts, not shown. An envelope 15 of glassis connected to a branch pipe of the manifold through a chipoff tube orportion 16. The opposite end of the manifold is connected to a vacuumpump, not shown, through a valve 17. A reservoir 20 of a gas to befilled in the envelope I5 is connected to the portion of the manifoldintermediate the valve 17 and chipoif tube 116 through a valve 18 and aflow rate adjusting valve 19. Supply of the operating substances iseffected while discharging the gas from the reservoir 20 into thesurrounding atmosphere by removing the closure plate lld. It isadvantageous to select the distance L between the inlet opening 21 ofthe gas and the opening 11 such that the gas flows through the manifoldin the form of a laminar flow although it is not always essential.Although distance L is determined according to the configuration of theclosable opening ill and the inner diameter of the manifold, suchcondition for laminar flow can be provided by selecting the distance Lto be equal to 5.7 X10, dRe, where d denotes the inner diameter of themanifold and Re the Reynolds number.

As a means for supplying an operating substance 22 (including a materialto be closed in the envelope) through opening .ll, a capsule 23 shown inH6. 3 may be utilized. Capsule 23 comprises a cylindrical sheath 2% madeof stainless steel and the like and a spindle 25 free to slide in thelongitudinal direction of the sheath. A depression 246 is formed one endof the spindle to carry the operating substance 22. and on the oppositesides of the depression there are provided circumferential grooves toaccommodate O-rings 27 and 27 which contact againstthe inner wall of thesheath 24 in an airtight fashion to prevent operating substance 22 fromcoming into direct contact with the atmosphere. As shown in FIG. 3,after being inserted to a suitable position in the manifold against theoutflow 28 of inert gas from reservoir 20, the capsule 23 is suitablyrotated to drop the substances 22 in the discharge tube.

With the above described apparatus, the discharge tube is manufacturedby the following steps. First, as shown in FIG. 2, the opening ll. isclosed and the interior of the system is evacuatedln this case thedischarge tube and selected portions of the system are suitably heated.After completion of evacuation, valve 18 is opened and valve is adjustedso as to charge the inert gas into the discharge tube under a pressureslightly higher than the atmospheric pressure. Thereafter, the opening11 is opened to cause the inert gas in the reservoir 26 to flow out intothe atmosphere and the flow rate of the gas is kept constant in asuitable range by additional adjustment of valve 19. On the other hand,sufficiently degassed and prepared operating substance 22 is put indepression 26 of capsule 23 in a dry box and is kept in afree-of-moisture state of atmosphere by sliding back the spindle 25 tothe position ready for use. Then, as shown in FIG. 3, the capsule isinserted into the manifold against the gas flow through the opening, andafter moving spindle 25 from the dotted line position to the solid lineposition where the depression 26 is to be immediately above the envelope15 shown in FIG. 3, the spindle is rotated to drop the operatingsubstance into the envelope. Then the capsule is removed from themanifold and the opening 11 is closed again. Thereafter, the envelope isevacuated to the desired pressure and then is taken in completion bysealing the chipoff portion.

Where the expensive gas is to be filled in, a source of cheaper inertgas is provided for the use of insertion of the capsule. In this case,however, the envelope has to be completely evacuated again just afterclosing operating substance 22 in the envelope 15, before the finalcharge of the proper gas under a required pressure.

Above described method is advantageous in the following points. Duringevacuation, since my operating substance is not contained in theevacuating system it is easy to evacuate the envelope to a sufficientlyhigh degree of vacuum (for example, to a pressure of 2 X10 torrs whichis required to provide necessary characteristics for discharge lampscontaining a vapor of mixed halogens). More particularly, as themoisture contained in the operating substance is not introduced in thetube during evacuation thereof, deleterious effect of the moisture canbe avoided. Since the operating substance to be closed does notdecompose and lose its quantity in the evacuating system, nonuniformityin the quality of finished lamps due to loss of the substance anddifficulty in evacuation caused by the decomposed products can beprecluded. Since the inert gas flows outwardly through opening 11 at thetime of introducing the operating substance, there is no fear thatimpurities in the atmosphere may enter into the discharge tube. Byutilizing a capsule as shown in FIG. 3 to introduce the operatingsubstance, even an extraordinary hygroscopic substance can be readilyclosed without being affected by moistures in the atmosphere. Since itis not necessary to provide many branch pipes, the construction of theevacuating system is simple and economic.

A modified embodiment of this invention is illustrated in FIGS. 4 to 6.As shown, an envelope of a discharge lamp is connected to a branch pipe31 projecting downwardly from the bottom of a cutoff cock 349 of glass,through an evacuating pipe 32. First and second evacuating systems 33and 34 are connected to the sidewall of the cutofi cock. These componentparts are combined such that rotation of a plug 33 of the cutoff cockselectively establishes communication between the first evacuatingsystem 33 and envelope l5 and communication among the three members 33,34 and i5. the first evacuating system 33 comprises a main pipe directlyconnected to cock 30 and a branch pipe connected to an intermediatepoint of the main pipe, said branch pipe being connected to a bomb 37containing an inert gas through a flow rate adjusting valve 36. The mainpipe is also connected to a first vacuum pump (not shown) through a flowquantity control valve 38. One end 39 of the second evacuating system isopened to fix a capsule 40 to be described later.

The evacuating system 34 includes bifurcated branch pipe 41 which isconnected to a second vacuum pump (not shown) and to a flow gasrecovering device (not shown) respectively through adjusting valves 42and 43. It is preferable to use a following device as said capsule or anadditive closing device 40. The capsule comprises an open endedcylindrical sheath of stainless steel and provided with an radiallyextending flange at one end, and a spindle 45 of stainless steel andadapted to be coaxially inserted into the sheath through said one end.The interior of the sheath 44 is sealed in the airtight fashion by meansof a fluorinated rubber packing 46 mounted on one end thereof and afluorinated rubber ring 47 mounted near the outer end of spindle 45. Thespindle can be moved axially or rotated about its axis by manipulating aknob secured to the outer end thereof extending beyond sheath 44. Adepression 48 for accommodating the additive or the operating substanceis formed on one side of spindle 44 near the movable packing ring 47.The operation of this modification is as follows.

First, cock 35 is operated to the position shown in FIG. 5 tointercommunicate the first evacuating system 33 with envelope 15 throughthe cock. While maintaining closed valve 36 for the inert gas bomb 37,valve 38 is opened to evacuate envelope l5 through the first evacuatingsystem 33. As above described, envelope l5 and other desired portionsare heated. On the other hand, an accurately weighed operatingsubstances, for example, a mixture of a metal halide and mercury isdeposited in depression 48 of spindle 45 of the capsule in a dry box.Then the capsule 40 is inserted into the second evacuating system 34through opening 39 with its movable packing ring 47 firmly engaged withthe inner wall of sheath 44 to seal the interior of sheath 44 from theatmosphere. After insertion, the capsule is secured by an O-ring (notshown) in an airtight fashion of the flange surrounding the opening andthe spindle is pushed into the system 34. Then flow gas recovering valve43 is closed while valve 42 for the second evacuating pump is opened toevacuate the interior of the second evacuating system and of sheath 44of the capsule 40. After completion of the evacuation step, valve 38 forthe first vacuum pump is closed and valve 36 associated with the inertgas bomb 37 is adjusted to introduce the insert gas into the firstevacuating system 33 and envelope 15 under higher pressure than theatmospheric pressure.

Then, after closing valve 42 for the second vacuum pump, plug 35 ofcutoff cock 30 is rotated to connect the second evacuating system 34 toenvelope I5 and first evacuating system 33. Valve 43 for the flow gasrecovering device is opened to cause the inert gas to flow through thesecond evacuating system 34. Then spindle 45 of capsule 44) ismanipulated to insert its inner end into cutoff cock 30 and whendepression 48 is brought to a position just above branch pipe 31 ofcutoff cock 30 the spindle45 is rotated to drop the additive containedin depression 48 into the envelope 15 as shown in FIG. 6. Thereafterspindle 45 is retracted into the second evacuating system, plug 35 isrotated in the opposite direction to disconnect the second evacuatingsystem 34 from cock 30, valve 36 of inert gas bomb 37 associated withthe first evacuating system 33 is closed and valve 3% of the firstvacuum pump is opened to remove the inert gas which has been admitted.Again, valve 33 of the first vacuum pump is closed and valve 36 isadjusted to introduce the inert gas into envelope 15 under apredetermined pressure, and the chipoff portion of exhaust pipe 32 issealed off to separate the envelope or a completed discharge lamp fromthe cock.

In this manner while evacuating the envelope by means of the firstevacuating system, the additive is weighed and deposited in the capsulein the dry box filled with a dried inert gas and the charged capsule isinserted into the second evacuating system. Immediately thereafter thesecond evacuating system is brought into operation. Thus the additive isat once subjected to vacuum, thus eliminating the effect of theatmosphere tending to deteriorate it. Once mounted, the capsule issealed against the atmosphere so that introduction of the moisture andother impurities from the atmosphere can be positively precluded. Thuscontamination by the atmosphere and introduction of moisture into thedischarge tube can be prevented. Yet the evacuation process of thedischarge tube, loading of the additive in the capsule and insertionthereof into the second evacuating system are effected simultaneously inparallel so that the interval of time required to fabricate the tube canbe greatly reduced. Since this also reduces the flow time of the inertgas it is possible to save the same. By recovering the inert gas itsconsumption is reduced. Further, the inert gas may be used to admitsubstances to be sealed in the evacuating system.

Each one of the first and second evacuating systems may comprise aplurality of evacuating circuits. Thus for example, the secondevacuating system may comprise a plurality of evacuating circuitsradially extending from the cutoff cock, one of said circuits being usedfor admitting mercury and the other, for example, a halide the firstevacuating system may also comprise a plurality of evacuating circuitsfor admitting different gases.

Thus, this invention provides a method and apparatus for manufacturingdischarge tubes which can evacuate discharge tubes to sufficiently highvacuum, can admit additive substances free from moisture into the tubeswithout being affected by the atmosphere, can correctly control thequantity of the additive, whereby to provide discharge tubes of uniformqualities in relatively short time. Moreover, consumption of the inertgas is small.

There will now be described the manner in which an evacuating system isnot contaminated by atmosphere when an inert gas is :discharged into theatmosphere from said system according to the method of the presentinvention.

The envelope was evacuated through the evacuating system with anordinary trap cooled by liquid nitrogen interposed between the inletopening 21 and branching portion of the manifold. The inert gas wasdischarged through the evacuating system into the atmosphere. After saidsystem was again evacuated, the trap was rewarmed therefrom. FIG. 7 is adiagram showing the gas pressure within the trap as measured by a vacuumgauge when the temperature of the trap was slowly raised. in FEG. 7, thegas pressure mmHg within the trap as measured by a vacuum gauge isrepresented by the ordinate and varied times (minute) at the inner wallof the trap by the abscissa. The results of the aforesaid determinationare denoted by a curve b.

On the other hand, the gas from the lamp envelope which is not yetcompletely degassed was measured in the same manner as described above,excepting that the inert gas was not discharged. The results seemed tobe harmless are in dicated by a curve a. The initial and second peaks onthe curves indicate an inert gas such as Ar or Ne. Such gases havinglower condensation temperature than that of H 9, are considered to benot harmful to lamp qualities. The curve b shows that though there stillremain some amounts of H after evacuation, such amounts will havesubstantially no harmful effect on the method of the present invention.

We claim:

1. Apparatus for manufacturing a discharge tube having an envelope inwhich an inert gas and an operating substance are sealed, comprising anevacuating pipe system in the form of a manifold including a closableopening; and means which is inserted into said evacuating pipe systemthrough said opening to supply an operating substance into said envelopewithout exposing said substance to the atmosphere, said manifold furtherincluding a first and a second flow circuits respectively connected to avacuum pump and to a source of said inert gas and a third circuit, oneend of said third circuit connected to said evacuating pipe systembetween said second circuit and said closable opening, the other end ofsaid third circuit being connected to said envelope through a chipoffportion.

2. The apparatus for manufacturing a discharge tube according to claimll wherein said evacuating pipe system has an auxiliary pipe systemwhich is connected to a second vacuum pump and provided with an openingadapted to receive said means for supplying said substance and means isprovided to selectively control the communication between said thirdcircuit and said first and second circuits and the communication betweensaid first, second and third circuits and said auxiliary evacuating pipesystem.

3. The apparatus for manufacturing a discharge tube according to claim 1wherein said means for supplying said operating substance to saidenvelope comprises an open ended cylindrical sheath, a spindle axiallymovable in said sheath and rotatable about the axis of said spindle, oneend of said spindle projecting outwardly through one end of said sheath,a depression provided on the periphery of said spindle near the otherend thereof to accommodate the substance and packings provided aroundthe periphery of said spindle on the opposite sides of said depressionto. seal said substance against atmosphere.

4. Apparatus for manufacturing a discharge tube having an envelope inwhich an inert gas and operating substance are sealed, comprising anevacuating pipe system in the form of a manifold including a closableopening; and means which is inserted into said evacuating pipe systemthrough said opening to supply an operating substance into said envelopewithout exposing said substance to the atmosphere, said manifold furtherincluding a first and a second flow circuits respectively connected to avacuum pump and to a source of said inert gas and a third circuit, oneend of said third circuit being connected to said evacuating pipe systembetween said second circuit and said closable opening, the other end ofsaid third circuit being connected to said envelope through a chipoffportion; said evacuating pipe system having an auxiliary pipe systemwhich is connected to a second vacuum pump and provided with an openingadapted to receive said means for supplying said substance; and means isprovided to selectively control the communication between said thirdcircuit and said first and second circuits and the communication betweensaid first, second and third circuits and said auxiliary evacuating pipesystem.

5. Apparatus for manufacturing discharge tube having an envelope inwhich an inert gas and an operating substance are sealed, comprising anevacuating pipe system in the form of a manifold including a closableopening; and means which is inserted into said evacuating pipe systemthrough said opening to supply an operating substance into said envelopewithout exposing said substance to the atmosphere, said manifold furtherincluding a first and a second flow circuits respectively connected to avacuum pump and to a source of said inert gas and a third circuit, oneend of said third circuit connected to said evacuating pipe systembetween :said second circuit and said closable opening, the other end ofsaid third circuit being connected to said envelope through a chipoffportion; said means for supplying said operating substance to saidenvelope comprises an open ended cylindrical sheath, a spindle axiallymovable in said sheath and rotatable about the axis of said spindle, oneend of said spindle projecting outwardly through one end of said sheath,a depression provided on the periphery of said spindle near the otherend thereof to accommodate the substance and packings provided aroundthe periphery of said spindle on the opposite sides of said depressionto seal said substance against atmosphere.

6. Apparatus for manufacturing a discharge tube having an envelope inwhich an inert gas and an operating substance are sealed, comprising, incombination: an evacuating pipe system including a closable opening;means which is inserted into said pipe system through said closableopening to supply an operating substance into said envelope withoutexposing said sub stance to the atmosphere; said means including anouter member and an inner member which is translatable and rotatablerelative to said outer member; a first flow circuit connected to avacuum pump; a second flow circuit connected to a source of inert gas;and a third flow circuit having one end thereof connected to saidevacuating pipe system between said second flow circuit and saidclosable opening, the other end of said third flow circuit beingconnected to said envelope through a chipoff portion.

7. Apparatus for manufacturing discharge tubes having an envelope inwhich an inner gas and an operating substance are sealed, comprising, incombination: an evacuating pipe system; a chipofi portion connectingsaid evacuating pipe system to said envelope; first means for evacuatingsaid evacuating pipe system and said envelope connected to saidevacuating pipe system through said chipotf portion; second means forsupplying said inert gas to said envelope through said evacuating pipesystem; third means for discharging said inert gas through an opening ofsaid evacuating pipe system; fourth means for inserting said operatingsubstance into said evacuating pipe system through said opening totransfer said substance into said envelope while said inert gas is beingdischarged through said opening; said operating substance beinghermetically sealed against the atmosphere; fifth means for adjustingthe pressure of said gas in said envelope to a predetermined value; andsixth means for sealing olT said chipoff portion to separate saidenvelope from said evacuating pipe system.

1. Apparatus for manufacturing a discharge tube having an envelope inwhich an inert gas and an operating substance are sealed, comprising anevacuating pipe system in the form of a manifold including a closableopening; and means which is inserted into said evacuating pipe systemthrough said opening to supply an operating substance into said envelopewithout exposing said substance to the atmosphere, said manifold furtherincluding a first and a second flow circuits respectively connected to avacuum pump and to a source of said inert gas and a third circuit, oneend of said third circuit connected to said evacuating pipe systembetween said second circuit and said closable opening, the other end ofsaid third circuit being connected to said envelope through a chipoffportion.
 2. The apparatus for manufacturing a discharge tube accordingto claim 1 wherein said evacuating pipe system has an auxiliary pipesystem which is connected to a second vacuum pump and provided with anopening adapted to receive said means for supplying said substance andmeans is provided to selectively control the communication between saidthird circuit and said first and second circuits and the communicationbetween said first, second and third circuits and said auxiliaryevacuating pipe system.
 3. The apparatus for manufacturing a dischargetube according to claim 1 wherein said means for supplying saidoperating substance to said envelope comprises an open ended cylindricalsheath, a spindle axially movable in said sheath and rotatable about theaxis of said spindle, one end of said spindle projecting outwardlythrough one end of said sheath, a depression provided on the peripheryof said spindle near the other end thereof to accommodate the substanceand packings provided around the periphery of said spindle on theopposite sides of said depression to seal said substance againstatmosphere.
 4. Apparatus for manufacturing a discharge tube having anenvelope in which an inert gas and operating substance are sealed,comprising an evacuating pipe system in the form of a manifold includinga closable opening; and means which is inserted into said evacuatingpipe system through said opening to supply an operating substance intosaid envelope without exposing said substance to the atmosphere, saidmanifold further iNcluding a first and a second flow circuitsrespectively connected to a vacuum pump and to a source of said inertgas and a third circuit, one end of said third circuit being connectedto said evacuating pipe system between said second circuit and saidclosable opening, the other end of said third circuit being connected tosaid envelope through a chipoff portion; said evacuating pipe systemhaving an auxiliary pipe system which is connected to a second vacuumpump and provided with an opening adapted to receive said means forsupplying said substance; and means is provided to selectively controlthe communication between said third circuit and said first and secondcircuits and the communication between said first, second and thirdcircuits and said auxiliary evacuating pipe system.
 5. Apparatus formanufacturing discharge tube having an envelope in which an inert gasand an operating substance are sealed, comprising an evacuating pipesystem in the form of a manifold including a closable opening; and meanswhich is inserted into said evacuating pipe system through said openingto supply an operating substance into said envelope without exposingsaid substance to the atmosphere, said manifold further including afirst and a second flow circuits respectively connected to a vacuum pumpand to a source of said inert gas and a third circuit, one end of saidthird circuit connected to said evacuating pipe system between saidsecond circuit and said closable opening, the other end of said thirdcircuit being connected to said envelope through a chipoff portion; saidmeans for supplying said operating substance to said envelope comprisesan open ended cylindrical sheath, a spindle axially movable in saidsheath and rotatable about the axis of said spindle, one end of saidspindle projecting outwardly through one end of said sheath, adepression provided on the periphery of said spindle near the other endthereof to accommodate the substance and packings provided around theperiphery of said spindle on the opposite sides of said depression toseal said substance against atmosphere.
 6. Apparatus for manufacturing adischarge tube having an envelope in which an inert gas and an operatingsubstance are sealed, comprising, in combination: an evacuating pipesystem including a closable opening; means which is inserted into saidpipe system through said closable opening to supply an operatingsubstance into said envelope without exposing said substance to theatmosphere; said means including an outer member and an inner memberwhich is translatable and rotatable relative to said outer member; afirst flow circuit connected to a vacuum pump; a second flow circuitconnected to a source of inert gas; and a third flow circuit having oneend thereof connected to said evacuating pipe system between said secondflow circuit and said closable opening, the other end of said third flowcircuit being connected to said envelope through a chipoff portion. 7.Apparatus for manufacturing discharge tubes having an envelope in whichan inner gas and an operating substance are sealed, comprising, incombination: an evacuating pipe system; a chipoff portion connectingsaid evacuating pipe system to said envelope; first means for evacuatingsaid evacuating pipe system and said envelope connected to saidevacuating pipe system through said chipoff portion; second means forsupplying said inert gas to said envelope through said evacuating pipesystem; third means for discharging said inert gas through an opening ofsaid evacuating pipe system; fourth means for inserting said operatingsubstance into said evacuating pipe system through said opening totransfer said substance into said envelope while said inert gas is beingdischarged through said opening; said operating substance beinghermetically sealed against the atmosphere; fifth means for adjustingthe pressure of said gas in said envelope to a predetermined value; andsixth means for sealing off said chipoff portion to separate saidenvelope frOm said evacuating pipe system.